package main

import (
	"flag"
	"fmt"
	"os"
	"strings"

	"gopkg.in/telegram-bot-api.v4"

	"github.com/pyed/transmission"
)

const VERSION = "0.0"

var (
	// flags
	BotToken string
	Master   string
	RpcUrl   string
	Username string
	Password string

	// transmission
	Client *transmission.Client

	// telegram
	Bot     *tgbotapi.BotAPI
	Updates <-chan tgbotapi.Update
)

// init flags
func init() {
	// define arguments and parse them.
	flag.StringVar(&BotToken, "token", "", "Telegram bot token")
	flag.StringVar(&Master, "master", "", "Your telegram handler, So the bot will only respond to you")
	flag.StringVar(&RpcUrl, "url", "http://localhost:9091/transmission/rpc", "Transmission RPC URL")
	flag.StringVar(&Username, "username", "", "Transmission username")
	flag.StringVar(&Password, "password", "", "Transmission password")

	// set the usage message
	flag.Usage = func() {
		fmt.Fprintln(os.Stderr, "Usage: transmission-bot -token=<TOKEN> -master=<@tuser> -url=[http://] -username=[user] -password=[pass]\n")
		flag.PrintDefaults()
	}

	flag.Parse()

	// make sure that we have the two madatory arguments: telegram token & master's handler.
	if BotToken == "" ||
		Master == "" {
		fmt.Fprintf(os.Stderr, "Error: Mandatory argument missing!\n\n")
		flag.Usage()
		os.Exit(1)
	}
}

// init transmission
func init() {
	// set transmission.Config, needed to establish a connection with transmission
	conf := transmission.Config{
		Address:  RpcUrl,
		User:     Username,
		Password: Password,
	}

	// transmission.New() never returns an error, we will ignore it and test with client.Session.Update()
	Client, _ = transmission.New(conf)
	if err := Client.Session.Update(); err != nil {

		// try to predict the error message, as it vague coming from pyed/transmission
		if strings.HasPrefix(err.Error(), "invalid character") { // means the user or the pass is wrong.
			fmt.Fprintf(os.Stderr, "Transmission's Username or Password is wrong.\n\n")

		} else { // any other error is probaby because of the URL
			fmt.Fprintf(os.Stderr, "Error: Couldn't connect to: %s\n", RpcUrl)
			fmt.Fprintf(os.Stderr, "Make sure to pass the right full RPC URL e.g. http://localhost:9091/transmission/rpc\n\n")
		}
		// send the vague error message too
		fmt.Fprintf(os.Stderr, "JSONError: %s\n", err)
		os.Exit(1)
	}
}

// init telegram
func init() {
	// authorize using the token
	var err error
	Bot, err = tgbotapi.NewBotAPI(BotToken)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Telegram Error: %s\n", err)
		os.Exit(1)
	}

	// get a channel and sign it to 'Updates'
	u := tgbotapi.NewUpdate(0)
	u.Timeout = 60

	Updates, err = Bot.GetUpdatesChan(u)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Telegram Error: %s\n", err)
		os.Exit(1)
	}
}

func main() {
	for update := range Updates {
		// ignore anyone other than 'master'
		if update.Message.From.UserName != Master {
			continue
		}
		// ignore edited messages
		if update.Message == nil {
			continue
		}

		// tokenize the update
		tokens := strings.Split(update.Message.Text, " ")
		command := strings.ToLower(tokens[0])

		switch command {
		case "list", "/list":
			// list torrents
		case "downs", "/downs":
			// list downloading
		case "active", "/active":
			// list active torrents
		case "errors", "/errors":
			// list torrents with errors
		case "trackers", "/trackers":
			// list trackers
		case "add", "/add":
			// takes url to a torrent to add it
		case "search", "/search":
			// search for a torrent
		case "latest", "/latest":
			// get the latest torrents
		case "info", "/info":
			// gets info on specific torrent
		case "stop", "/stop":
			// stop one torrent or more
		case "stopall", "/stopall":
			// stops all the torrents
		case "start", "/start":
			// starts one torrent or more
		case "startall", "/startall":
			// starts all the torrents
		case "stats", "/stats":
			// print transmission stats
		case "speed", "/speed":
			// print current download and upload speeds
		case "del", "/del":
			// deletes a torrent but keep its data
		case "deldata", "/deldata":
			// deletes a torrents and its data
		case "help", "/help":
			// prints a help message
		case "version", "/version":
			// print transmission and transmission-telegram versions
		default:
			// no such command, try help

		}
	}
}